Hi! I posted this bug report on the WoWAce forums before finding this portal. So, here's a copy and paste:

I've found a problem in Cartographer_Quests while doing the new Dustwallow Marsh quests. For some quest givers, it records additional quests that aren't there. These false quests appear as mere numbers, such as "1" or "60", when we right-click the exclamation mark. Also, they don't have a submenu, or rather, and empty submenu, so it's not possible to delete them. As a result, the yellow exclamation mark stays in the map, even if we have completed all the quests available for that quest giver.

Here's an example of how these fake quests end up recorded in the saved variables file:

I guess this is due to some change Blizzard implemented in whatever is the way quest names are recorded. So, it would be interesting to see Cartographer_Quests get a way to cleanup these wrong entries before writing them down, as well as providing us a way to manually delete in game any such case that remains.